In known plug connections of this type the portion of the pin inserted into the sleeve, i.e. the plug shank, is either of cylindrical or of conical shape, and the interior of the sleeve into which the pin is inserted is shaped cylindrical or conical to match the shape of the pin shank. The pin can be a single pin or a forked pin.
Conical pins have the disadvantage that the elimination of the locking force between shank and sleeve is effected directly in the beginning of lift-off of the respective tooth or jaw segment, i.e. the frictional engagement is eliminated at the moment when the segment is lifted. Moreover, the conical embodiment, on the one hand, effects harsh friction in the final position and, on the other hand, insufficiently safeguarded retention prior to or during lifting of the tooth or jaw segment.
In contrast thereto, the cylindrical plug shanks--even though there the engagement between plug shank and sleeve also extends along the length of a long shank--show that complete elimination of the locking force between plug shank and sleeve is achieved only when the plug shank is completely withdrawn from the sleeve--i.e. in order to completely overcome the adhesive force between plug shank and sleeve it is necessary to completely lift off the tooth or jaw segment along the full length of the pin shank. Aside from the considerable force required for dislodging the tooth or jaw segments from the pattern base, segments including a plurality of pins, or composite patterns on tooth stumps, are highly prone to misalignment which may be due to even minor irregularities in the parallel alignment produced in drilling the locking hole or gluing the locking shank in position. This usually occurs in divergent or convergent stump preparations or tooth axis positions.